The effect of the structure of polychlorinated biphenyls on their hydroxylation, oxidation, and glutathionyl conjugation reactions.

OBJECTIVE: To compare the nature of the metabolites formed from the phase I metabolism (hydroxylation and oxidation) and phase II metabolism (glutathionyl conjugation) of PCBs that have different chlorine substitution patterns. To discuss the structure-activity relationships and metabolic mechanisms of PCBs. METHODS: 4-Cl-biphenyl (PCB3), 4,4'-Cl-biphenyl (PCB15), 3,4,3',4'-Cl-biphenyl (PCB77) were used for in vitro metabolic study. LC/MS and UV-Vis studies were performed for metabolites identification. RESULTS: The cytochrome P-450 catalyzed hydroxylation rate decreased as the number of chlorine substitutions increased. In this reaction, PCB3 was fully metabolized, approximately half of the PCB15 was metabolized and PCB77 was not metabolized at all. The oxidation rate of PCB15-HQ was higher than that of PCB3-HQ under various oxidation conditions. The LC/MS and UV-Vis data suggest that in the conjugation reaction of PCB15-Q and GSH, the Michael addition reaction occurs preferentially over the displacement reaction. CONCLUSION: The metabolic profiles of polychlorinated biphenyls (PCBs) are dramatically affected by chlorine substitution patterns. It is suggested that the metabolic profiles of PCBs are related to their chlorine substitution patterns, which may have implications for the toxicity of PCB exposure.

Additions to the Genus Helicosporium (Tubeufiaceae, Tubeufiales) from China with an Identification Key for Helicosporium Taxa.

Helicosporous hyphomycetes is a group of filamentous fungi that shows promising application prospects in metabolizing bioactive natural compounds. During a study of helicosporous fungi in China, six new helicosporous taxa were collected and isolated from decaying wood in Guangxi Zhuang Autonomous Region, China. Morphological comparisons with multi-gene phylogenetic analyses revealed that these six taxa belong to Helicosporium (Tubeufiaceae, Tubeufiales), and they were recognized as three novel species and were named Helicosporium liuzhouense, H. multidentatum, and H. nanningense. Detailed descriptions and illustrations of the newly discovered taxa and comparisons with similar fungi are provided. In addition, a list and a key to accepted Helicosporium species are provided.

Lignicolous Freshwater Fungi from Plateau Lakes in China (I): Morphological and Phylogenetic Analyses Reveal Eight Species of Lentitheciaceae, Including New Genus, New Species and New Records.

During the investigation of lignicolous freshwater fungi in plateau lakes in Yunnan Province, China, eight Lentitheciaceae species were collected from five lakes viz. Luguhu, Qiluhu, Xingyunhu, Cibihu, and Xihu lake. Based on morphological characters and phylogenetic analysis of combined ITS, LSU, SSU, and tef 1-α sequence data, a new genus Paralentithecium, two new species (Paralentithecium suae, and Setoseptoria suae), three new records (Halobyssothecium phragmitis, H. unicellulare, and Lentithecium yunnanensis) and three known species viz. Halobyssothecium aquifusiforme, Lentithecium pseudoclioninum, and Setoseptoria bambusae are reported.

[Cloning and expression of the pig fast skeletal muscle troponin C gene].

A pig skeletal muscle expressed sequence tag (EST, accession number BM083186) was found to encode amino acid sequences with high homology to human TNNC2. In silico cloning obtained a 843 bp sequence which we named pig fast skeletal troponin C gene (TNNC2). The open reading frame of TNNC2 was between nucleotides 201 - 683, and was confirmed by RT-PCR. The gene encoded a 160 amino acid residue protein and had the highest similarity with human and mouse homologues, with percent identities being 93.6%, 90.5%, respectively. Semi-quantitative RT-PCR analysis of mRNA from different normal tissues indicted that the TNNC2 gene was expressed in the skeletal muscle and the levels of expression were higher in the longissimus dorsi of the Duroc pig than in the same tissue of the Lantang pig.

[Identification of differential expression ESTs in pig muscle tissue by DHPLC].

The differential expression ESTs in muscle tissue of Large Yorkshire pig and Lantang pig, one of the local pig breeds in Guangdong province, were identified with DHPLC system and graphic analysis software LabWork4.0, and both methods verified the true differential display bands. The results showed that DHPLC can quickly and accurately detect differential expression mRNA profiles of different tissues, and can be widely used to study mRNA expression, differential expression of different animal tissues under variant environments.